Abstract: In this talk, I will present new ways to search for new physics in the proton fixed-target experiments, including neutrino experiments and the newly proposed FerMINI experiment. I will focus on detecting the minicharged particles (MCPs) in these experiments. A large flux of MCPs are produced in the proton beam and can be detected through electron scattering or scintillation signatures. Searches for MCPs constitute a test of charge quantization and a probe for low-energy consequences of fundamental theories, including grand unification theory and certain string compactification scenarios. Furthermore, MCP can account for dark matter abundance, and provide a plausible explanation to the EDGES 21-cm anomalous absorption spectrum.
If time permits, talk will include light scalars, dark photons, dipole portal heavy neutral leptons, and dark neutrinos, as explanations of anomalies like MiniBooNE excess and proton charged radius anomaly. I will show that proton fixed-target experiments are nature sites to search for these weakly interacting and long-lived particles.
This talk is mainly based on arXiv:1806.03310 (PRL’18) and arXiv:1812.03998. See also arXiv:arXiv:1706.00424 (PLB’18), arXiv:1803.03262 (PRD’18), and 1812.08768.